Frequent mapping and unmapping a buffer object adds overhead for modifying the page table and creates debug output. Unmapping a buffer is only required when the memory manager evicts the buffer from its current location.
v4: * WARN_ON if buffer is still mapped during BO cleanup
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de --- drivers/gpu/drm/drm_gem_vram_helper.c | 49 ++++++++++++++++++++++----- include/drm/drm_gem_vram_helper.h | 4 +++ 2 files changed, 45 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c index 1e17f11cc7b9..0990f0e03213 100644 --- a/drivers/gpu/drm/drm_gem_vram_helper.c +++ b/drivers/gpu/drm/drm_gem_vram_helper.c @@ -28,6 +28,7 @@ static void drm_gem_vram_cleanup(struct drm_gem_vram_object *gbo) */
WARN_ON(gbo->kmap_use_count); + WARN_ON(gbo->kmap.virtual);
drm_gem_object_release(&gbo->bo.base); } @@ -356,18 +357,17 @@ EXPORT_SYMBOL(drm_gem_vram_kmap);
static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo) { - struct ttm_bo_kmap_obj *kmap = &gbo->kmap; - if (WARN_ON_ONCE(!gbo->kmap_use_count)) return; if (--gbo->kmap_use_count > 0) return;
- if (!kmap->virtual) - return; - - ttm_bo_kunmap(kmap); - kmap->virtual = NULL; + /* + * Permanently mapping and unmapping buffers adds overhead from + * updating the page tables and creates debugging output. Therefore, + * we delay the actual unmap operation until the BO gets evicted + * from memory. See drm_gem_vram_bo_driver_move_notify(). + */ }
/** @@ -497,6 +497,38 @@ int drm_gem_vram_bo_driver_verify_access(struct ttm_buffer_object *bo, } EXPORT_SYMBOL(drm_gem_vram_bo_driver_verify_access);
+/** + * drm_gem_vram_bo_driver_move_notify() - + * Implements &struct ttm_bo_driver.move_notify + * @bo: TTM buffer object. Refers to &struct drm_gem_vram_object.bo + * @evict: True, if the BO is being evicted from graphics memory; + * false otherwise. + * @new_mem: New memory region, or NULL on destruction + */ +void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, + bool evict, + struct ttm_mem_reg *new_mem) +{ + struct drm_gem_vram_object *gbo; + struct ttm_bo_kmap_obj *kmap; + + /* TTM may pass BOs that are not GEM VRAM BOs. */ + if (!drm_is_gem_vram(bo)) + return; + + gbo = drm_gem_vram_of_bo(bo); + kmap = &gbo->kmap; + + if (WARN_ON_ONCE(gbo->kmap_use_count)) + return; + + if (!kmap->virtual) + return; + ttm_bo_kunmap(kmap); + kmap->virtual = NULL; +} +EXPORT_SYMBOL(drm_gem_vram_bo_driver_move_notify); + /* * drm_gem_vram_mm_funcs - Functions for &struct drm_vram_mm * @@ -506,7 +538,8 @@ EXPORT_SYMBOL(drm_gem_vram_bo_driver_verify_access); */ const struct drm_vram_mm_funcs drm_gem_vram_mm_funcs = { .evict_flags = drm_gem_vram_bo_driver_evict_flags, - .verify_access = drm_gem_vram_bo_driver_verify_access + .verify_access = drm_gem_vram_bo_driver_verify_access, + .move_notify = drm_gem_vram_bo_driver_move_notify, }; EXPORT_SYMBOL(drm_gem_vram_mm_funcs);
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h index 4f0e207ee097..b47c46516466 100644 --- a/include/drm/drm_gem_vram_helper.h +++ b/include/drm/drm_gem_vram_helper.h @@ -112,6 +112,10 @@ int drm_gem_vram_fill_create_dumb(struct drm_file *file, void drm_gem_vram_bo_driver_evict_flags(struct ttm_buffer_object *bo, struct ttm_placement *pl);
+void drm_gem_vram_bo_driver_move_notify(struct ttm_buffer_object *bo, + bool evict, + struct ttm_mem_reg *new_mem); + int drm_gem_vram_bo_driver_verify_access(struct ttm_buffer_object *bo, struct file *filp);